Within the field of metal cutting tools used in turning, grooving, parting and threading operations, cutting inserts removably securable in an insert holder have long since provided a way of performing a cutting operation with a suitably hard material, i.e. cemented carbide, in the vicinity of the cutting edge, where the insert holder, manufactured from a less hard material, is reusable following the disposal of a worn or damaged cutting insert.
This type of cutting tool has been further developed to utilize indexable cutting inserts with an increased number of cutting edges, giving economic benefits from providing an increased number of cutting operations per cutting insert. This type of cutting tool has also been developed to provide a more stable and secure means of retaining the indexable insert within the insert holder.
U.S. Pat. No. 6,612,207 discloses an indexable cutting-off bit having four cutting parts and four prismatic chambers. As shown in FIG. 2 of this patent, each prismatic chamber includes two spaced-apart abutment locations, where for each index position of the cutting-off bit in a holding element, three of the eight spaced-apart abutment locations are in contact with three corresponding surfaces at forwardly projecting upper and lower protrusions of the holding element.
U.S. Pat. No. 5,203,648 discloses an indexable cutting insert having a substantially square shape with four cutting edges. The cutting edges are arranged on a first pair of opposed sides of the cutting insert, where each of the opposed sides has a pair of cutting edges separated by an intermediate contact surface. Additional contact surfaces perpendicular to the intermediate contact surfaces are located on a second pair of opposed sides of the cutting insert. For each index position of the cutting insert within an insert holder, one of the intermediate contact surfaces and one of the additional contact surfaces are in clamping contact with the insert holder.
U.S. Pat. No. 6,942,434 discloses an indexable cutting insert having two opposing side surfaces and a peripheral edge surface extending therebetween. The peripheral side surface has five abutment sections and five equally spaced apart cutting portions. For each index position of the cutting insert within an insert pocket of an insert holder, two of the five abutment sections abut upper and lower support walls of the insert pocket. The upper and lower support walls form an acute angle diverging in a direction towards the operative cutting portion of the cutting insert.
U.S. Pat. No. 7,597,508 discloses an indexable cutting insert having two opposing end surfaces and a peripheral side surface located between the end surfaces. The peripheral side surface is divided into five identical segments, each segment having a cutting section, a leading wall and a trailing wall. For each index position of the cutting insert within a forward securing portion of an insert holder, trailing, leading and trailing walls of three consecutive segments respectively abut and bear against first, second and third supports of a securing surface of the forward securing portion. The first and second supports diverge downwardly, and the second and third supports diverge rearwardly.